Photographic antiplumming agents and compositions containing them



Patented Oct. 27, 1953 PHOTOGRAPHIC ANTIPLUMMING AGENTS AND COMPOSITIONSCONTAINING THEM Edward B. Knott and Philip K. Brooks, Harrow,

England, assignors to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey No Drawing. Application October 25, 1951,Serial No. 253,206. In Great Britain March 30, 1951 9 Claims.

This invention relates to improvements in the production of photographicimages, especially images on paper supports prepared from silver halideemulsions.

Silver halide emulsions are frequently subject to image degradationduring processing, that is, during development, fixing, washing, toning,or other treatment and during the moist heat to which they are subjectedon drying, as when prints are subjected to ferrotyping or hot-typeglazing. This degradation of the image frequently manifests itself asplumming or bronzing of the image.

It is known that Z-acetylthioglycolamidobenzthiazole having thefollowing formula:

can be employed as an anti-plumming agent for photographic silver halideemulsions. Moreover, the alkaline hydrolysis product of the abovecompound:

II. S

is an efficient anti-plumming agent. Attempts to isolate the free thiol:

III. S

o-phenylene, o-naphthylene, etc., which may be which can be representedby the following general formula:

IV. s

/ R D ONHC O-llH-SR;

wherein D represents an arylene group, e. g. o-phenylene, o-naphthylene,etc., which may be unsubstituted or substituted, for example, with analkyl (e. g. methyl, ethyl, etc.) and/or alkoxyl (e. g. methoxy, ethoxy,etc.) group, R represents an alkyl group, e. g. methyl, ethyl, etc. andR1 represents an acyl group, e. g. acetyl, propionyl, etc. can behydrolyzed in alkaline media to give hydrolysates which not only areeffective antiplumming agents, but which, upon prolonged standing,develop only a faint yellow colour and show no increase in desensitizingproperties.

It is, therefore, an object of our invention to provide a means forpreventing image degradation in an exposed silver halide emulsion. Stillanother object is to provide new chemical compounds. Another object isto provide a method for making these new compounds. Another object is toprovide photographic silver halide emulsions containing these newcompounds. Other objects will become apparent from a consideration ofthe following examples and description.

Accordingly, the present invention provides a method of preventing imagedegradation of an exposed silver halide emulsion during processing whichcomprises performing one or more of the steps of developing, fixing,washing and drying an exposed silver halide emulsion in the presence ofone or more compounds represented by the following general formula:

wherein D represents an arylene group, e. g.

unsubstituted or substituted, for example, with, alkyl (e. g. methyl,ethyl, etc.) and/or alkoxyl (e. g. methoxy, ethoxy, etc.) groups, Rrepresents an alkyl group, e. g. methyl, ethyl, etc., and R2 representsa hydrogen atom or a metallic atom, such as a sodium atom, potassiumatom orother alkali metal atom.

When any of the above compounds represented by Formula V areincorporated in silver halide .5 Example6.--2-a-mercaptopropionamido-fimethoxybenzthiaeole Example7.-6-chloro-2-a-mercaptopropionamidobenzthiazole ToZ-amino-d-chlorobenzthiazole (6.7 g.) in dioxane (30 cc.) was addedquinoline (4.7 g.), then a-acetylthiopropionyl chloride (6.0 g.). After2 hours standing water (150 cc.) was added to give an oil. This washydrolysed in ethanol (25 cc.) by adding a solution of sodium hydroxide(3.5 g.) in water (125 00.). The solid obtained on acidification formeda cream microcrystalline powder, M. P. 183-186" C. from benzene.

Example 8. 2-a-mercaptobutyramidobenzthiazOZe Z-aminobenzthiazole (7.5g.) was dissolved in dioxane (50 cc.) by warming, quinoline (6.5 g.) wasadded, and stirring rapidly, aacetylthio butyryl chloride (9.0 g.)dripped in over 10 minutes at 25 C. Quinoline hydrochloride separatedrapidly. After completed addition the mixture was stirred for 2 hoursand poured into water (250 00.). A thick yellow oil was precipitated. Itwas taken up in chloroform and the solvent distilled oil. The residualoil was dissolved in ethanol (50 cc.) and a solution of sodium hydroxide(6.0 g.) in water (250 cc.) added at 25 C. After 2 minutes water (250cc.) was added, the liquor clarified by ether extraction and therequired thiol precipitated as a semisolid with dilute hydrochloricacid. This was washed by decantation, redissolved in 0.5N-sodiumhydroxide, clarified by ether extraction and precipitated as a hardsolid by acidification. It was collected, washed with water and airdried. From benzene it formed cream needles, M. P. 142-146 C.

The a-acetylthiobutyryl chloride used in Example 8 was prepared as shownin the following example:

Example 9.a-Acetylbutyrylchloride a-Acetylthiobutyric acid (73 g.) wastreated at 2025 C. with thionyl chloride (67.4 g.), stood overnight,excess thionyl chloride distilled off at 6065 C. under reduced pressure(20 mm.) and the oil distilled from the steam bath at '70- 72 C./9 mm.

The a-acetylthiobutyric acid used in Example 9 was prepared as shown inthe following example:

Example 10.-a-Acetylthiobutyric acid a-Mercaptobutyric acid (52 g.) wasplaced in a 250 cc. B-necked flask fitted with stirrer and droppingfunnel and acetic anhydride (75 cc.) run in over 10 minutes at roomtemperature. It was stirred for minutes, then the solvent removed underreduced pressure on the steam bath. The oil was then fractionated,collected at 100 150 C./8 mm. then redistilled and collected (37 g.) at143-149" C./8 mm.

Other compounds represented by Formula V above can also be usedeffectively according to our invention.

What {we claim as our invention and desire secured by Letters Patent ofthe United States is:

1. The method of preventing image degradation of an exposed silverhalide emulsion during processing, which comprises performing at leastone of the steps of developing, fixing, washing and drying said emulsionin the presence in said emulsion of from 2.5 grams to 25 grams per unitof silver halide formed from 1000 grams of silver nitrate, of a compoundselected from those represented by the following general formula:

D c-NH-o o- H-SR,

\N/ wherein R represents an alkyl group, R2 represents a member selectedfrom the group consistingof a hydrogen atom and an alkali metal atom,and D represents an arylene group.

2. The method of preventing image degradation of an exposed silverhalide emulsion during processing, which comprises performing at leastone of the steps of developing, fixing, washing and drying said emulsionin the presence in said emulsion of from 2.5 grams to 25 grams per unitof silver halide formed from 1000 grams of silver nitrate, of a compoundselected from those represented by the following general formula;

wherein R represents an alkyl group containing from 1 to 2 carbon atoms,R2 represents a member selected from the group consisting of a hydrogenatom and an alkali metal atom, and D represents a phenylene group.

3. The method of preventing image degradation of an exposed silverhalide emulsion during processing, which comprises incorporating in atleast one of the developing, fixing and washing baths used to processsaid emulsion, an appreciable amount but not more than 5%, of a compoundselected from those represented by the following general formula:

wherein R represents an alkyl group containing from 1 to 2 carbon atoms,R2 represents a member selected from the group consisting of a hydragonatom and'an alkalirmetal-atom, and D represents a-phenylene group, andprocessing said exposed emulsioninsaid-bath.

5. A photographic silver halide emulsion containing from 2.5 to 25 ramspenu i Of Silver halide formed from 1000,grarns;of; silver nitrate, ofahompound selected from those represented by the following generalformula:

wherein R represents an alkyl group, R2 represents a member selectedfrom the group consisting of a hydrogen atom and an alkali metal atom,and D represents anary-lene group. i 6.- A photographicsilver halideemulsion oon taming fromw2.5 110.25 rams per unit of silver halideformed from 1000 gramsof silver nitrate, of s. compound; selected fromthose represented by the following general formula:

wherein R. represents an alkyl group containing from '1' to 2 carbonatoms, R2 represents a member selected from the group consisting of ahydrogen atom and an alkali metal atom, and D repre'sents'a phenylenegroup. I

'7. A photographic silver halide emulsion containing from 2.5 to 25grams per unit of silver halideformed from 1000, gram lei-silvernitrate, of-a, oompoundseleoted from those represented by the followinggeneral formula:

C NH C ZH-BR:

wherein R2 represents a member selected from the group consisting of ahydrogen atom and D represents an arylene group.

8. A photographic silver halide emulsion containing from 2.5 to 25'grams per unit of silver halide formed from 1000 grams 'of silvernitrate, of a compound selected from those represented by the followinggeneral formula:

wherein R2 represents a member selected from the group consisting of ahydrogen atom and Drepresents an arylene group. 9. A photographic silverhalide emulsion containingjrom 2.5 grams per unit to 25 grams per unitof silver halide formed from 1000 grams of silvernitrate of acompoundselected from the group consisting of2-a-mercaptopropionamidobenzthiazole, '2-'o.-mercaptopropionamido-6-ethoxybenzthiazole, 2-a-mercaptopropionamido- 6-methoxybenzthiazo1e, 6Ch 1QI0-2-a-II1BICaptO propionamidobenzthiazole, "zfamercaptobutyramidob'enz'thiazole, and alkali metal salts of saidcompounds.

. EDWARDiB. KNOTT.

PHILIP K. BROOKS.

References Cited in the file of'this patent UNITED STATES PATENTS NumberName Date 2,040,928 Engelmann May 19, 1936 2,051,145 Lubs et a1. Aug.18, 1936 2,282,005 Sheppard et al'. May 5, 1942 2,311,103 Weyerts Feb.16, 1943

1. THE METHOD OF PREVENTING IMAGE DEGRADATION OF AN EXPOSED SILVERHALIDE EMULSION DURING PROCESSING, WHICH COMPRISES PERFORMING AT LEASTONE OF THE STEPS OF DEVELOPING, FIXING, WASHING AND DRYING SAID EMULSIONIN THE PRESENCE IN SAID EMULSION OF FROM 2.5 GRAMS TO 25 GRAMS PER UNITOF SILVER HALIDE FORMED FROM 1000 GRAMS OF SILVER NITRATE, OF A COMPOUNDSELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: